It is known in the art to provide lighting equipment for photographic studios, with a constant or continuous light illuminating the subject well enough for the photographer to place the subject in a desirable position and to focus the camera, and a supplementary flash light to provide the illumination necessary for taking the photograph. It is desirable to make the continuous or constant light adjustable to various degrees of brightness, and to vary the amount of light given off by the flash device, in accordance with the adjusted value of the continuous light.
In known constructions of this kind, a voltage divider is connected with the means for adjusting the brightness of the continuous light, so that the storage capacitor of the flash unit is charged up to a voltage of given value, corresponding to the brightness or intensity to which the continuous light is set. In this way, the amount of energy stored in the flash capacitor is so determined that upon discharge of the capacitor through the flash tube, the light radiated by the flash tube produces an illumination of the object to be photographed which as a whole provides for an exposure of the object being photographed corresponding to the distribution of light upon the illumination of the object by the continuous light.
If it is desired, after setting the continuous light to a given value of illumination, to reduce the brightness of the illumination, then an additional discharge circuit must be provided (in these devices of the prior art) so that the flash capacitor which was previously charged to a higher voltage upon the initial higher setting of the continuous light, can be discharged to a lower voltage value, before making the flash exposure. In addition to this, upon varying the continuous or focusing light, a given waiting time must always be allowed, so that the storage capacitor can charge or discharge, as the case may be, to the proper voltage value corresponding to the value of illumination of the continuous light.
An object of the present invention is to simplify and improve the prior art constructions of this same general type, by eliminating the need for varying the charge on the storage capacitor when the brightness of the continuous light is varied, and eliminating the need for allowing a waiting time after the continuous light is adjusted to a new value, before the flash is available for use. At the same time, it is an object of the invention also to do away with the previously required discharge circuit for partial discharge of the storage capacitor in order to decrease the voltage thereof, when the light output of the continuous light is adjusted to a lower value.